Control valves of a hydrostatic steering system

ABSTRACT

The valves are associated and integrated inside a body C comprising:  
     The steering valve includes two cylinders A and B, concentric with the steering shaft D; the cylinder A to roll conjointly with the said shaft. The said valve controls the direction of the fluid circulation in the cylinders which effect the steering.  
     The safety valve includes the pistons P1, P2 and the spring S, and makes easier the control, only manual of the said steering in an occasional lack of fluid pressure (pump damage, fluid leak, cut of the shaft strap, engine stop).  
     The progression valve includes a cylinder and the piston PV; it operates by means of the vacuum effect TV, produced in the engine air admission of the vehicle, controlling the return of the said piston P1 in a progressive way, from a certain speed of the said vehicle.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention refers to the association of news types of valves of control of a fluid circulation, applied to hydrostatic steering systems.

[0003] 2. Description of the Related Art

[0004] In the previous technique, the valves include fluid circuits situated in the very steering shaft, which results in a smaller capacity of circulation of the said fluid; the circuits connections do not have well-defined limits, which results in a lesser definition of the control of the direction of the fluid circulation; other difficulties are the small orifices and the strangulation which reduce the said capacity of the fluid circulation between the cylinders which effect the steering direction.

[0005] In an occasional lack of the fluid pressure (pump damage, fluid leak, cut of the shaft strap, engine stop) the reciprocal circulation of the fluid between the said cylinders is very difficult and the fluid pressure reaches a high value, which makes difficult the manual correction of the steering direction; a great insecurity in the hydrostatic steering systems may derive from that situation.

OBJECTIVES OF THE INVENTION

[0006] The objective of the present invention is to solve the previously mentioned difficulties by obtaining a greater capacity of the fluid circulation and a higher definition of the limits of the circuits connections, in the steering valve; to obtain a greater facility of the manual control of the steering by means of a safety valve; and to obtain the progressive hydrostatic control of the steering by means of a progression valve.

INVENTION SUMMARY

[0007] The valves are associated and integrated inside a body C and include a first valve, of steering, which controls the direction of the fluid circulation in the cylinders which effect the steering a second valve, of safety, which controls the direct and reciprocal circulation of the fluid between the said cylinders, and a third valve, of progression, which controls the effects progression of the said second valve, FIGS. 19 and 20.

[0008] The steering valve includes two cylinders A and B, concentric with the steering shaft D, the cylinder A to roll conjointly with the said shaft, FIG. 1, 2 and 3; channels 1, 2, 3, 4 and 5 are inserted in the contiguous peripheries of the said cylinders, constituting circuits sets, each set with independent fluid circulation and whose fluid debits are gathered in collectors, FIGS. 4 to 9, and 20.

[0009] The safety valve is integrated in axial position with the steering valve and includes the pistons P1 and P2 and the spring S, FIGS. 19 and 20; it is connected to the steering cylinders by connections T3 and T4 with high capacity of fluid circulation, FIGS. 1 to 3; when there is lack of the fluid pressure the said spring S perform the return of the said pistons, it allows the free fluid circulation between the said steering cylinders and makes easier the control, only manual, of the said steering, FIGS. 19 and 20.

[0010] The progression valve includes a cylinder and the piston PV, connected to the cylinder and the piston P2, the said pistons are connected by a central shaft; it operates by means of the vacuum produced in the engine air admission of the vehicle, controlling the return of the said piston P1 in a progressive way, from a certain speed of the said vehicle, FIGS. 19 and 20.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The FIG. 1, shows the steering valve in a radial section being the shaft DO and the cylinder A in the neutral position; it also shows the piston P1 of the safety valve in the return position allowing the free fluid circulation between the cylinders of the steering system by terminals T3 and T4.

[0012] The FIG. 2, show the cylinder A and the shaft rotating in the way D1; the fluid impulsion is transmitted to one of the cylinders of the steering system by terminal T3; the fluid return of the opposite cylinder is received by terminal T4.

[0013] The FIG. 3, shows the cylinder A and the shaft rotating in the inverse way D2; the fluid impulsion is transmitted by terminal 4 and the return is received by terminal T3.

[0014] The FIG. 4, 5 and 6, are schemes which show the channels position of a set of the fluid circuits and corresponding connections of the steering valve; when the shaft is in the neutral position D0 the fluid impulsion is directed from terminal T1 to terminal T2, connected to the return circuit of the fluid; in the position D1 the fluid impulsion is directed from terminal T1 to terminal T3 and the fluid return from terminal T4 to terminal T2; in the position D2 the fluid impulsion is directed from terminal T1 to terminal T4 and the fluid return from terminal T3 to terminal T2.

[0015] The FIG. 7, 8, and 9, correspond to the schemes of the FIG. 4, 5 and 6, and respectively show in axial section the overlapping of the channel extremities 1 over the channels extremities 2, 3 and 4, being performed the terminal connections T1 with the terminals T2, T3 and T4.

[0016] The FIG. 10, 11 and 12, reproduce the schemes of the FIG. 4, 5 and 6; line (U—V) indicates the position of the radial position of the radial sections represented by FIG. 13, 14 and 15; line (X-Y) indicates the position of the radial sections represented by FIG. 16,17 and 18.

[0017] The FIG. 13, 14 and 15, show in axial section, according to the line (U—V) and the shaft positions D0, D1 and D2, the relative position of the channels inserted in the contiguous peripheries of the cylinders A and B.

[0018] The FIG. 16, 17 and 18, identically show, according to the line (X—Y) and the said shaft positions, the relative position of the respective channels.

[0019] The FIG. 19 shows in axial section the advanced position of the pistons P1 and P2 of the safety valve by means of the fluid pressure; it also shows the position of the cylinder and of the piston PV of the progression valve.

[0020] The FIG. 20 shows in axial section the back position of the pistons P1 and P2 of the safety valve by means of the spring S and of the piston PV.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0021] The steering, safety and progression valves are associated and integrated inside a body C; the said body has terminals T1 and T2 of normal capacity of fluid circulation for the connection with the pump, FIGS. 19 and 20 ; it has terminals T3 and T4 of higher capacity of fluid circulation for the connection with the cylinders which effect the steering direction, FIG. 1, 2 and 3.

[0022] The steering valve is constituted by a first cylinder A and by a second one B concentric with the steering shaft, positions D0, D1 and D2.

[0023] The first cylinder to roll conjointly with the shaft by means of the attrition produced by the pressure of the laminar springs F introduced in slots, inserted in a symmetrical position, in the internal periphery of the said first cylinder A.

[0024] The rotation of the first cylinder A, in relation to the second cylinder B, is limited by bolts E symmetrically fixed in the said second cylinder and prolonged for slots inserted in the said first cylinder; the said slots have a radial section, which permits the rotation of the said cylinder A, in one direction or in inverse direction, so that the exact overlapping of the contiguous extremities of connection of the said channels may be obtained.

[0025] Channels 1, 2, 3, 4 and 5 in axial position are inserted in the contiguous peripheries of the cylinders. The channels have got a small width, and connected sets of channels are formed in which the connection extremities of each channels are extensive and contiguous permitting their exact overlapping and being obtained the maximum exactness of the limits of the corresponding channels connections; to each channels set corresponds a set of fluid circuits and their connections; the exact overlapping and the greater extension of the said circuits connections permit the increase in the fluid circulation and the decrease in the corresponding pressure; the maximum exactness of the limits of the said channels connections permits the obtaining of a safe control of the direction of the fluid circulation.

[0026] Four channels sets are preferably inserted in a radial and symmetrical position; each set has got openings corresponding to the external connection terminals T1, T2, T3 and T4; the homologous openings are connected to circular collectors inserted in the external periphery of the second cylinder B; the position of each collector is corresponding to the said terminals, of entrance or of exit of the fluid in the circuits, FIG. 7, 8, 9,19 and 20.

[0027] Channel 1 is inserted in axial position in the internal periphery of the second cylinder in connection with terminal T1; channel 2 is inserted in the external periphery of the first cylinder in the line of the channel 1 and in connection with terminal T2; channels 5, and the transversal channel of their interconnection, are inserted in the internal periphery of the second cylinder and in connection with terminal T2; channel 3 and its extension are inserted in axial position in the external periphery of the first cylinder in connection with terminal 4, FIGS. 10 to 18.

[0028] The valve receives the fluid impulsion of the pump through terminal T1, the fluid return to the pump is performed through terminal T2, FIGS. 19 and 20; terminals T3 and T4 communicate with their respective cylinders which effect the steering direction by means of connections of higher section, FIG. 1, 2 and 3.

[0029] The description of the functioning of the steering valve relates only to one set of circuits since the functioning of the other sets is identical.

[0030] When the shaft is motionless, position D0:—the channels of the steering valve are kept in intermediate position; the upper extremity of the channel 1 is adjusted by overlapping to the contiguous extremity of channel 2 and the fluid impelled by the pump freely circulates from the entrance terminal T1 to the exit terminal T2 returning to the pump, FIG. 1, 4 and 7.

[0031] The steering shaft runs in the direction of the position D1:—the lower extremity of the channel 1 is adjusted by overlapping to the channel extension 3 and the impulsion of the fluid accepted by terminal T1, is transmitted by the exit terminal T3 to the respective steering cylinder; at the same time, the fluid of the opposite cylinder returns to the pump through the terminal T4 connection to the terminal T2, FIG. 2, 5 and 8.

[0032] The steering shaft runs in the inverse direction, position D2:—identically, the lower extremity of the channel 1 is adjusted by overlapping to the channel 4 extension and the impulsion of the fluid accepted by terminal T1 is transmitted by the exit terminal T4 to the respective cylinder which effect the steering change in the inverse direction; at the same time, the fluid of the opposite cylinder returns to the pump through terminal T3 connection to the terminal T2, FIG. 3, 6 and 9.

[0033] The safety valve is constituted by the connection of the pistons with a different diameter P1 and P2, and by their respective cylinders situated in an axial and external position, to the second cylinder of the steering valve, FIG. 19 and 20.

[0034] The cylinder of the less diameter piston P1 communicates by means of the said connections, of substantial section, in the transversal position T3 and T4 with the cylinders which performs the steering direction, FIG. 1, 2 and 3; the cylinder of bigger diameter P2 communicates with the entrance collector of the fluid in the steering valve and receives the fluid impulsion through the corresponding terminal T1; the respective pressure, acting on the said piston P2, surpassing the resistance faced by the piston P1 and by the spring S, impels the said piston P1 in order to interrupt the free fluid circulation through the steering valve, FIG. 19. The terminal R allows the respiration of the piston cylinder P2, and is preferably connected to the fluid tank.

[0035] If there is a lack of the fluid emission (pump damage, cut of the shaft strap, engine stop) and the pressure on the piston of bigger diameter P2 is annulled, the spring S expansion will perform the piston 1 return and the free fluid circulation will be reestablished between the steering cylinders allowing an easy steering control, manual only, without the hydrostatic support of the steering valve, FIGS. 1 and 20.

[0036] The progression valve is constituted by the cylinder and its piston PV centred and connected to the cylinder and the piston P2; the said pistons are connected by means of a central shaft, FIGS. 19 and 20.

[0037] The progressive vacuum effect admitted by the terminal TV acts on said piston PV in order to obtain a depression force, progressively increasing and superior to the resistance faced by the pressure on the piston P2, being performed the pistons P1 and P2 return in a progressive way; the said return, allowing the direct fluid circulation between the steering cylinders in a progressive way, performs the progressive reduction of the steering hydrostatic control, FIG. 20.

[0038] By establishing an adequate relation between the pistons P1, P2 and PV diameters, the spring force, and the values of the fluid pressure and of the vacuum effect, it is obtained a progressive reduction of the steering hydrostatic control from a certain speed of a vehicle. 

1. Control valves of a hydrostatic steering system, including a steering valve, a safety valve and a progressive valve, being associated and integrated in a external body C in order to control a hydrostatic steering system, FIG. 1, 2, 3, 19 and 20, wherein: the steering valve includes a first cylinder A and a second cylinder B concentric with the steering shaft, positions D0, D1 and D2; the first cylinder A to roll conjointly with the said shaft by means of springs F and its rotation in relation with cylinder B is limited by means of bolts E, FIG. 1, 2 and 3; channels 1, 2, 3, 4, and 5 are inserted in the contiguous peripheries of the said cylinders; the said channels form connected sets and each set has an independent fluid circulation, FIGS. 4 to 12; the safety valve includes the cylinders and their pistons P1 and P2 and the spring S; it is integrated in axial position and connected to the valve and the steering cylinders, FIGS. 19 and 20; the progression valve includes the cylinder and its piston PV connected to the piston P2 of the safety valve and operates by means of the vacuum effect produced in the engine admission, FIGS. 19 and
 20. 2. Control valves, according to claim 1, wherein the first cylinder to roll conjointly with the rotation of the steering shaft, positions D0, D1 and D2, by means of attrition produced by the pressure of the said springs F introduced in slots; the said slots are inserted in an axial and symmetrical way in the internal periphery of the said first cylinder A, FIG. 1, 2 and
 3. 3. Control valves, according to claim 1, wherein the rotation of the first cylinder A in relation to the second cylinder B is limited by the said bolts E, since they are symmetrically fixed in the said second cylinder and prolonged to slots inserted in the said first cylinder; the radial section of the said slots corresponds to the radial sections of the bolts and of the channels allowing the said cylinder A rotation in one direction or in the inverse direction so that the exact overlapping of the contiguous extremities of connection of the said channels may be obtained.
 4. Control valves, according to claim 1 wherein the said channels are inserted in axial position in the contiguous peripheries of the said cylinders and have got a small width; connected sets of channels are formed in which the connection extremities of each channel are extensive and contiguous being obtained the maximum exactness of the limits of the corresponding channels connections; to each set of the said channels corresponds a set of fluid circuits and their connections; the greater extension of the said connections permits the increase in the fluid circulation and the decrease in the respective work pressure; the maximum exactness of the limits of the corresponding channels connections permits the obtaining of a safe control of the direction of the fluid circulation.
 5. Control valves, according to claim 1, wherein each channels set has got openings corresponding to the external connection terminals T1, T2, T3, and T4; the homologous openings are connected to fluid collectors inserted in the external periphery of the second cylinder in circular positions corresponding to the said terminals.
 6. Control valves, according to claim 1, wherein in the said safety valve, the cylinders and their pistons P1 and P2, are connected and have got different diameters; the cylinder of the smaller diameter piston communicates by means of connections of the substantial section and in the transversal position T3 and T4, with the cylinders which perform the steering, FIG. 1, 2 and 3; the cylinder of the bigger diameter piston P2 communicates with the entrance collector of the fluid in the steering valve and receives the fluid impulsion through the corresponding terminal T1, FIG. 19; the respective pressure, acting on the piston P2, surpassing the resistance faced by the piston P1 and by the spring S, impels the said piston P1 in order to interrupt the free fluid circulation between the said steering cylinders and to permit the control of the fluid circulation through the steering valve, FIG.
 19. 7. Control valves, according to claim 6, wherein when there is a lack of the fluid pressure on the piston of bigger diameter P2 the spring S expansion performs the piston return P1; the said return re—establishes the free fluid circulation between the steering cylinders allowing an easy steering control, manual only, without the support of the steering valve, FIG.
 20. 8. Control valves, according to claim 1, wherein in the progression valve, the cylinder and its piston PV are centred and connected to the cylinder and its piston P2; the said pistons are connected by means of a central shaft; the progressive vacuum effect admitted by the terminal TV acts on the corresponding piston PV in order to obtain a depression force, progressively increasing and superior to the resistance faced by the pressure on the piston P2, being performed the pistons PI and P2 return in a progressive way; the said return, allowing the direct fluid circulation between the steering cylinder in a progressive way, produces a progressive reduction of the steering hydrostatic control.
 9. Control valves, according to claim 8, wherein establishing an adequate relation between the pistons P1, P2 and PV diameters, the spring S force, and the valves of the fluid pressure and of the depression of the vacuum effect, it is obtained a progressive reduction of the steering hydrostatic control from a certain speed of a vehicle. 